It has long been recognized that bot flies represent a health hazard to horses as, if the eggs are ingested, the larvae of such flies become attached to a horses stomach and later are discharged with manure. Typically, the adult fly emerges therefrom in mid summer and during its short seven to ten day life apan, up to five hundred eggs are laid on the horse's hair, generally in the lower leg area. As a horse attempts to remove the eggs by biting or licking, the eggs are ingested.
Proper care of a horse requires that its coat be regularly examined during the critical mid summer period for deposits of bot eggs and any observed deposits be promptly removed. The eggs are about the size of a strawberry seed and are yellow-orange. While such eggs may be scraped from the shafts of hairs using one's finger nails, other procedures are obviously preferable.
One such procedure is to shave the infected area, a procedure that is objectionable, particularly in the case of show horses because shaved areas would be noticeable. Another method is to treat the infected area with a chemical that attacks the glue-like mulare deposited on the hair along with the eggs. This procedure is effective but somewhat messy. Yet another procedure is a spun glass block that is effective but difficult to use.